Invited Presentation

Dust-obscured galaxies/AGNs viewed with Subaru Hyper Suprime-Cam survey

Author(s): Yoshiki Toba (ASIAA) and HSC DOGs project members

Presenter: Yoshiki Toba (ASIAA)

Dust-Obscured Galaxies (DOGs) are optically-faint, but infrared (IR)-bright objects at z~2. Their mid-IR (MIR) flux densities are three orders of magnitude larger than those at optical wavelengths, which implies dust heating by significant star formation (SF), an active galactic nucleus (AGN), or both, and the bulk of the optical and ultraviolet (UV) emission from them is absorbed by dust.

Recently, some works have reported that the brighter MIR DOGs are more AGN-dominated, and indicated that black holes in the IR-bright DOGs are expected to show the highest accretion rate during a major merger event. In addition, IR-bright DOGs could tend to reside in richer environments than fainter ones, and the most luminous DOGs may evolve into brightest cluster galaxies. Therefore, particularly IR-bright DOGs are expected to be a crucial population in terms not only of the co-evolution of galaxies and supermassive black holes (SMBHs) but also of structure formation. However, efficient searches for luminous DOGs have been difficult in previous surveys due to their faintness in the optical and low surface densities. Therefore, high-sensitivity and wide-area surveys in both optical and MIR are required to search for the most IR-bright DOGs.

In this talk, I will present our recent studies on IR-bright DOGs based on the Subaru Hyper Suprime-Cam (HSC) and Wide-Field Infrared Survey Explore (WISE). In particular, I will focus on their statistical properties such as IR luminosity function, IR luminosity density, and clustering properties (Toba et al. 2015, PASJ, 67, 86; Toba et al. 2017, ApJ, 835, 36).